On a less, ah, abstract level:
Exercise. Hard. If you’ve got nothing else, just start jogging and keep going until you’re so tired that all you can think about is one leg in front of the other. When you’re exhausted to the point of taking all your mental energy to get that last rep up, or one more step, you have no room for stressful things. When you’re done you’ll feel like you have a new perspective.
Wow I really feel like going for a run now. Maybe I’ll squeeze one in before class tonight. I haven’t exercised in sooo long it would probably do me a world of good.